Underfeed stoker



Apr. 3, 1923.

v Filed May 6, 1918 1,45@,5% R. A. FORESMAN UNDERFEED STOKER 2 sheets-sheet l R. A. FORESMAN UNDERFEED STOKER Filed May s,

1918 2.5heets-shcet Z Wim l Patented pr. 3, i923.

ROBERTA. FORESMAN, OFlCI-IICAGO, ILLINOIS, ASSIGNOR TO WESTINGHOUSE ELEC-- TRIO & MANUFACTURING COMPANY, A CORPORATION OIE- PENNSYLVANIA.

UNDERFEED STOKER.

Application med may e, 191s. serial NQ. 232,804.

To all ywhom t may concern.'

Be it known that I, ROBERT A. FORESMAN, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have made a new and useful In` vention in Underfeed Stokers, of which the.

following is a specification.

This invention relates to improvements in underfeed stokers and has for an object to produce means for overcoming difficulties which have heretofore been encountered with such stokers.

In the drawings accompanying and forming a part hereof Fig. l is a fragmental perspective view of a well known type of underfeed stoker and illustrates the stoker equipped with an embodiment of my invention.

Fig. 2 is a perspective view of a section of an air distributing box which forms a detail of the stoker illustrated in Fig. 1.

Fig. 3 is a perspective view of a fuel deecting cap forming a detail of the present invention.

Fig. 4 is a fragmental longitudinal sectional view of a stoker illustrated in Fig. 'l and illustrates the fuel deecting cap in place within the stoker.

' taken along a broken line so as to illustrate the passage 9 and one of the caps 13 in section.)

Referring to Fig. l; it will be apparen that the stoker there illustrated consists of alternately arranged fuel deliveringretorts 5 andI air supplying, fuel supporting por-` tions 6, both of which extend from the front to the rear of the furnace. As illustrated,vthe retorts 5 are downwardly inclined toward the rear of the furnace and the fuel supportingportions are similarly inclined and are made up of a plurality of separate twyer blocks 7. Each air supplying, fuel supporting portion 6, hereinafter for brevity and distinction in description termed a fuel supporting surface. comprises a series of twyer blocks 7 located in overlapped and stepped relation. In addition to this.'each twyer block is so formed that it, with an adjacent twyer bloc-k, forms al series of air deliveringr` passages which are adapted to deliver air into the retort across the normal lineof move-ment of fuel from the retort and also to deliver air toward the rear of the furnace and in the general direction of movement of the fuel through the (The section is furnace. To accomplish this each twyer block is arched andis provided around its forward and lateral edge with a number of serrations or c-orrugations which form air delivery passages, between adjacent t-wyers, and communicate with an air box located below the fuel supporting surfaces of the furnace. As shown inF ig. l, the lateral walls 5a of adjacent retorts are spaced so as to form an air delivery space 7a which is in open communication with the air chamber below the fuel supporting surfaces. This space 7 is bridged by the twyer blocks 7. A fuel hopper 8 is shown located at the front of the furnace and communicating with each separate retort through ai fuel delivery passage 9 which diverges, in a vertical plane, from its throat or narrower po'rtion to its outlet within t-he combustion chamber of the furnace. In the Stoker illustrated, fuel -i's fed from the through thel fuel delivery passage and into the furnace by means of a ram l0, which is adapted to be this purpose.

From the above it will be apparent that the general direction of movement of the fuel from the hopper into the furnace is along the axes of the retorts. It will be understood. however, that in normal operation, a fuel bed of considerable depth is maintained within the furnace and thatl the mouths of the fuel delivery passages 9 are located below the upper line of the fuel bed and that fuel is consequent-ly fed into the furnace below the combustion zone. In Fig, 4 of the drawings the irregular line approximately illustrates the upper level of the fuel bed. nder such operating conditions it will be apparent that fuel. fed into the retorts is gradually forced upwardly and out of the retorts by the incoming fuel. so that in general the retorts are filled with green coal and coal subjected to preliminary or vpartial distillation by thevsensible heat ,of

hopper periodically reciprocated for I delivery porti'on of each of the fuel delivery passages 9. The air supplying openings12 are, however, located above the passage 9 and are arranged so as to direct the flow of air issuing from them into the upper portion of the fuel bed or into the space immediately above the fuel bed.

It is the common practice in multiple retort stoker construction to lock each series of twyei1 blocks lwith an upper fiat lockingY 'me-mbei. locking member approximates in contourthe external contour of the twyer blocks .and forms a shelf on which the fuel entering from the delivery passage into the retort may collect.

It 'has been found that some .grades 'of Ifuel' cause. smoke to be discharged from .l fthe furnace'through the fuel delivery pt sagesdnto tl'ie boiler room. This .difficulty 'has been encountered with several typesof underfeed stokers.

An. object of my invention .is izo-.prevent smoke issuing from the furnace intoV the boiler room. A

In .accomplishing this object, I have eliminated the possibility of fuel collecting and remaining at the upper end of' In other.

the fuel supporting surfaces. words, I have prevented fuel `from `collecting in pockets or on surfaces which are not in direct lines of travel` of the 'fuel movingthrough the furnace by replacing the Ausual locking member with a fuel defiecting cap 18. illustrated in perspective vin- 40 Figure 3. -This'prevents fuel entering the furnace from being held in a morepor less permanent position, where it is slowly coked bythe heat of the furnace'.

By employing a cap, such as is illustrated in Fig..3,.I-have overcome the difficulty encountered Vwith-'the old form of locking menibenand I believe that this is due to the fact that the cap bridges theV space between the uppermost twyer' block and the front wall of ,thestoken or as illustrated, the space between the uppermost twyer block and the air box. In addi-tion to this, the cap is of suchA contour that it Will not only prevent fuel from lodgin being retained while subjecte to a coking temperature, but will also direct the fuel issuing from the passage 9 into a portion 0f the fuel bed where itis burned under satisfactory conditions yof draft and4 fuel bed movement.

In addition to the above, I believe-the fact .that the "caps form, in effect, extensions' of the fuel delivery passages 9 alsoaids in 4It may also be possi on it and overcoming the obpcti'onal phenomenon.4

caps prevents the formation ofv objectionable air pockets or eddies within the fuel bed,

`and that it is therefore effective in aidingto direct the flow of 'air ,along proper lines of iow. v

I am fully convinced, however, that any means which prevents fuel from lodging in pockets near the front of the furnace and also guides or directs the fuel .into fuel bed, a portion subjected to a well defined rearward movement will, in a large measure, accomplish the desired results. this reason I do not wish to limit myself to the structural details illustrated and hereinafter described.

As shown in Fig. 4 the cap 13 forms a locking member for the series oftwyer blocks forming the fuel supporting surface of which the cap forms a part. In this respect it replaces and performs the function of thev usual locking member. Tlieforward andlateral faces of .tlie.cap are of such For contour that they bridge the spa-ce between the innermost portion ofthe air box 11 and the uppermost twyer block i', and are so formed that .they present a surface on 'which fuel cannot lodge and be retained. In addition to this, each cap is provided with forwardly projecting. ears 15 vwhich engage adependingbraclret 11 ofthe air box 11 and cooperatelwith the air box tol form an extension ofthe adjacent fuel delivery passage 9. As shown in Fig. 4, the cap is provided with an interior chamber 16 which, like the twyer blocks, receives air from the airspace 7a bridged by the twyer blocks and the` cap. This air is delivered into the furnace through outlets provided betweenithe lower faceofv the cap andthe uppermost twyer block which. outlets, as -illustra.ted,`are formed by corrugations 17.

'Each cap vis held in place .by means of a A`bolt 18, which enga-ges `aportion of the frame l'of the Stoker. This bolt-clamps the cap 'in place on the, uppermost twyer block and .therefore locks all ofthe twyer blocks iii place. This arrangement is similar to theerrangeinent usually employed Ain connection with locking members, 'now coinmonly in use, and a specific description of the means employed for mounting thetwye'rs is therefore not necessary.

iio

` While I have described and illustrated but' one modification of 'my invention; it

"will be apparent to those skilled in the art that various modifications',v change-s, additions and omissions .may be made in the apparatus described and illustrated without departing from.the spirit and scope of the invention as'set forth by the appended claims. v 'V i That I claim is :v A 1. In a furnace, incombination in an underfeed stoker, a downwardly inclined fuel feeding retort extending from the front wall of the furnace toward the'rear of the Stoker, a fuel supporting air delivering `means located on each side of said retort, a fuel feeding hopper located at the front of the furnace and communicating with said retort, fuel feeding mechanism operating to force fuel from said hopper into said retort, a fuel guidemember forming a cap for each fuel supporting air delivering means and a con- -tinuation of the .fuel feeding passage be- 2. In a furnace, in 'combination in an underfeed stoker, a downwardly inclined fuel retort extending from the front wall of the furnace toward the rear ofthe furnace, a

on each side of said'retort and extending downwardly from the front toward the rear `fuel supporting air delivering means locatedof the furnace, a fuel deliverypassage for,

delivering fuel fromthe front of the furnace into said retort .and a fuel directing capy topping each fuel supporting air delivering means and forming a guide for fuel entering said passage, said fuel directing cap having an exposed surface extending forwardly and upwardlyT from the fuel supporting air delivering means to the .effective front wall surface ata greater angle of inclination than that of said fuel supporting air delivering means, whereby the lodgment of fuel and the formation of. pockets at the upper end portion of the fuel supporting air delivering means. are prevent-ed.

In a furnace, invcombination in an underfeed st-oker, a downwardly inclined fuel retort extendingfrom vthe front wall of the furnace toward the rear of the Stoker, a downwardly inclined fue] supporting air delivery means locatedon each'side of said retort and comprising a series of over-lapping twyer blocks located in stepped relation and arranged to deliver air in to said retort. a twyer locking member topping eachseries of twyer blocks and located at the front of said furnace and filling the space between the upper twyer block and the ef fective front wall of the furnace, said locking member having an exposed surface inclined forwardly and upwardly from the effective surface of the -uppergtwyer block of each series to the front wall of the fur- *nace at a greater angle of inclination than that of said series of twyer blocks.

from the front `wall of thel furnace toward the rear of the furnace. a fuel hopper located at the front of the furnace, and coinmunicating through Aa fuel delivery passage with said retort, and a fuel supporting means located on each side of the said retort an'd extending downwardly from the fron't toward the rear of the furnace. tlie upper portion of each of the said fuel supporting means extending to the effective front wall of the furnace at an angle of inclination greater than-that of the main fuel supporting means and forming a fuel detlecting extension of the said fuel delivery passage.

5. In a furnace` an underfeed Stoker comprising a fuel retort extending from the front Vall toward the rear of the furnace, a hopper' communicating with, said retort through a fuel delivery passage, an air distributing box' located above the retort and extending across the front' of the furnace transversely of said reto-rt and a separate fuel supporting air deliverymeans located on each side of` said retort and extending downwardly from the front toward the rear of the furnace, each of said f'uel supporting air delivery means being topped by. means bridging the space between the air box and the upper portion ofthe fuel supporting air delivery means at a greater angle of inclinavtion than that of the fuel supporting air delivery means and forming` a fuel deflecting extension of said fuel delivery passage.

` 6. In a furnace, the combination with an underfeed Stoker having alternate fuel feeding retorts and series of fuel supporting twyers extending downwardly and rear- \wardly from the frontwall of the furnace and having a t ansverse air box overhanging the front enc of said retorts and twyers, of a fuel guide member mounted on the upper twyer of each series of twyers in close' contact with the'air box and having asurface sloping rearwardly from the effective air box surface-to .the twyers at a greater angle of inclination than that of the series of twyers. 4

7. In a furnace, the combination with an underfeed stoker having -alternate fuel feeding retorts and series of fuel supporting twyers extending downwardly and rearwardly from the front wall of the furnace, andvhavinga transverse air box overhanging the front ends of the'said retorts and twyers. ofa 4fuel guide member mounted on the upper twyer of each series of twyers in close contact with the air box and having a convex surface sloping radially from the effective air box surface to the twyers at a greaterangle of inclination than that of the series of twyers.

8. In a furnace. the .combination with a multiple retort underfeed stoker having alternate fuel feedingretortsand series of fuel supporting twyers extending downto the twyers at a greater angle of inclina-v tion than that of the series of twyers. y

9. In a furnace, the combination with an underfeed stoker having alternate fuelfeeding retorts and series of twyers inclined downwardly and rearwardly fromv the front wall of the furnace, of atwyer locking block crowning the twyers andserving as a fuel defleeting fillet at the. point of joinder A of each series of twyers with the front wall,

whereby fuel lpassing from the retort is directed into paths of fuel movement, the said block having a rearwardly sloped exposed surface having a greater angle' of inclination than that of the series of twyers.

10.' An article of manufacture for use in `a furnace. of the multiple retort underfeed type having alternate fuel-feeding retorts and series of fuel-supporting twyers extending downwardly and rearwardly from the front wall of the furnace consisting in a fuel-guiding, twyer-locking member tIiaving a bottom surface adapted to cooperate with an upper surface of the uppermost twyer of a series, a forward surfaceadapted to conform to the eHective front -wall surface of the furnace and havinga rearwardly iiielined exposed surface having a greater angle of inclination than the critical angle of repose of the fuel for which the Stoker is adapted. i A,

In testimony whereof, I have hereunto1 subscribed my name this 2nd day of May, 1918.

l .ROBERT-A, FoREsMAN.

' Witnesses:

R, L. IRVIN,

O. I. BARNELL. 

